1. Field of the Invention
The present invention relates to an antivibration device suitable for a toe correction bushing and the like for use in, for example, a suspension of a car.
2. Description of the Prior Art
A toe correction bushing is known. For example, Japanese Unexamined Patent Publication No. HEI 11-201209 (1999) discloses the toe correction bushing comprising an inner cylinder, an outer cylinder disposed outside the inner cylinder for engagement, an elastic body provided between the two cylinders, and a circular plate-shaped stopper member welded to the axial end of the inner cylinder, wherein the stopper member is provided at part of its outer periphery with an inclined plane, and the outer cylinder is provided at part of its one end with an inclined plane facing the inclined plane of the stopper member. In this case, when the outer cylinder is moved in the axial direction toward the stopper member by lateral force, the axial movement of the outer cylinder is controlled by the inclined planes of the stopper member and the outer cylinder to cause it to be displaced in the direction perpendicular to the axis.
An antivibration device such as the toe correction bushing is displaced in the direction perpendicular to the axis by the input of a lateral force in the axial direction. Accordingly, it is necessary to provide a displacement controlling means comprising a stopper means, an inclined member provided inside the elastic body or the like and it is required for the displacement controlling means to effectively carry out the displacement in a direction perpendicular to the axis. Moreover, it is required to easily control the displacement characteristics in the direction perpendicular to the axis in accordance with the purpose of use. It is therefore an object of the present invention to realize these requirements.
The stopper member of the above-mentioned embodiment is made of a plate-shaped member welded to an axial end of the inner cylinder and integrated with the outer cylinder by the elastic body which is injected between the inclined plane of the outer cylinder and the inner cylinder. In this case, the inner cylinder is first integrated with the stopper member before injection of the elastic body and then, the outer cylinder is integrated with these by injection of the elastic body. Accordingly, even though it is required to change characteristics of the stopper member in accordance with the purpose of use so as to change the characteristics of toe correction, such a change is difficult. It is therefore another object of the present invention to easily carry out the change of a stopper member.
The conventional toe correction bushing described above is displaced in the direction perpendicular to the axis by the input of a lateral force in the axial direction. Accordingly, it is necessary to provide a recess or the like to reduce the spring constant of the elastic body, thereby making the displacement easy. However, in this case, since the amount of displacement in the axial direction is increased relative to the lateral force, the amount of displacement in the direction perpendicular to the axis is relatively decreased. On the other hand, if the spring constant of the elastic body is increased, it affects the riding quality. This means that there is an upper limit on the spring constant itself of the elastic body. Accordingly, it is required to have a construction with directional properties so that the spring constant of the elastic body itself is not so increased, but the spring constant can be increased only in the case of toe correction. It is therefore the other object of the present invention to realize these requirements.
According to the invention of claim 1, an antivibration device is provided, which comprises an inner cylinder, an outer cylinder disposed outside the inner cylinder for engagement, an elastic body provided between the two cylinders, and a stopper member adapted to control the axial movement of one of the two cylinders when receiving external force and to displace it in the direction perpendicular to the axis, characterized in that the stopper member is separately provided from the two cylinders and the elastic body, and secured to the axial end of the inner cylinder.
According to the invention of claim 2, the outer cylinder is provided at part of its axial end with an outwardly opening inclined section, and the stopper member is provided with a stopper projection adapted to engage the inner space of the inclined section.
According to the invention of claim 3, an antivibration device is provided, which comprises an inner cylinder, an outer cylinder disposed outside the inner cylinder for engagement, an elastic body provided between the inner and outer cylinders, and a displacement control means for displacing an input to the direction perpendicular to the axis when one of the two cylinders receives the input in the axial direction, characterized in that an intermediate ring is integrally embedded in the elastic body between the two cylinders and is provided with an inward projecting section, which projects to the inner cylinder side, for serving as the displacement control means, and that a recessed section is provided at a position of the elastic body opposite to the intermediate ring relative to the axis in a cross-section of the inner cylinder in the axial direction.
According to the invention of claim 4 according to claim 1, the antivibration device is characterized in that the inward projecting section is integrally formed with the intermediate ring, or is formed as a separate body to be mounted on the intermediate ring for integration.
According to the invention of claim 5 according to claim 3 or claim 4, the antivibration device is characterized in that the inner cylinder is provided, in the axial direction, with an outward projecting section facing and with some distance from the inward projecting section and part of the elastic body is disposed between the inward projecting section and the outward projecting section.
According to the invention of claim 6 according to one of claims 3 through 5, the antivibration device is characterized in that the inward projecting section and the recessed section, or these and the outward projecting section are provided right and left to be symmetrical in a cross-section of the inner cylinder in the axial direction with respect to a point on the axis.
According to the invention of claim 1, the stopper member is separately provided from the inner and outer cylinders and the elastic body. Accordingly, it is possible to easily obtain necessary characteristics only by selecting the most suitable stopper member corresponding to the purpose of use relative to a main body consisting of the two cylinders and the elastic body which are integrated in advance and by installing the stopper member at the axial end of the inner cylinder.
According to the invention of claim 2, the stopper member is provided with a stopper projection. The stopper projection is inserted into a space inside of the inclined section provided at the axial end of the outer cylinder and caused to face the inclined section. By the input of external force, the inclined section contacts the stopper projection to compress it. As a result, by the counterforce of the stopper projection, the inner and outer cylinders are caused to be relatively displaced in the direction perpendicular to the axis. In this manner, it is possible to easily change the characteristics only by changing the material or shape of the stopper projection.
According to the invention of claim 3, the intermediate ring is provided with the inward projecting section, and the elastic body is provided with the recessed section which is located on the opposite side relative to the inner cylinder. Accordingly, when an input in the axial direction is applied, the inward projecting section compresses the elastic body to generate a force in the direction perpendicular to the axis, wherein the recessed section accelerates the displacement by this force in the direction perpendicular to the axis. In this manner, by providing the intermediate ring, the spring constant of the elastic body itself is not so increased, but the spring constant in the case of displacement in the axial direction can be increased thanks to the existence of the intermediate ring. This means that the directional properties can be applied to the spring constant and a sufficient amount of displacement in the direction perpendicular to the axis can be realized for the input in the axial direction. Further, it is not only possible to simplify the shape of the outer cylinder, but also to make the outer shape of the entire device compact.
According to the invention of claim 4, the inward projecting section can be integrally formed by forming part of the intermediate ring, or can be formed as a separate body to be mounted on the intermediate ring for integration. Thus, it is possible to easily realize the inward projecting section.
According to the invention of claim 5, the inner cylinder is provided with an outward projecting section facing and with some distance from the inward projecting section in the axial direction of the inner cylinder, and part of the elastic body is disposed between the inward projecting section and the outward projecting section. In this manner, the elastic body is compressed between the inward projecting section of the intermediate ring and the outward projecting section of the inner cylinder by the input in the axial direction. As a result, a large force in the direction perpendicular to the axis can be generated by the counterforce of the elastic body to increase the amount of displacement in the direction perpendicular to the axis.
According to the invention of claim 6, the inward projecting section and the recessed section, or these and the outward projecting section are provided right and left to be symmetrical in a cross-section of the inner cylinder in the axial direction with respect to a point on the axis. In this manner, since a symmetrical construction is realized in the axial direction, even when the antivibration devices according to the present invention are provided in pairs on the right and left side of a body, these can be used in common by reversing the device right and left.